Fire Index (BC Forestry Service)
Rank 1: Smouldering ground fire; red, hot embers but few flames
Rank 2:  Flames low to the ground
Rank 3: Moderately vigorous with flames up to one metre
Rank 4: Highly vigorous with some tree-top flames
Rank 5: Extremely vigorous with tree-top flames travelling up to 50 metres a minute
Rank 6: Flames up to 200 metres above the tree tops and racing 100 metres / minute; 150 km/h winds inside the fire